The present invention relates to a speaker device.
The present application claims priority from Japanese Application No. 2005-221810, the disclosure of which is incorporated herein by reference.
Generally, when a speaker is to be fixed to an attachment base such as a vehicle, an attachment member (an attachment bracket) is often used to complete such a fixation (for example, refer to Japanese Unexamined Patent Application Publication No. 2003-274473).
As shown in FIG. 1, a speaker device 1J comprises: a magnetic circuit including a frame 10, a plate 11 attached to the bottom of the frame 10, a magnet 12, and a yoke 13; a voice coil 14 disposed within a magnetic gap formed between the frame 11 and the yoke 13 and driven by an electric signal supplied thereto; a voice-coil bobbin 15 wound by the voice coil 14; a damper 16 supporting the voice-coil bobbin 15 on the frame 10; a diaphragm 17 having its inner perimeter supported on the voice-coil bobbin 15 and outer perimeter supported through its edge portion 17A on the outer perimeter 10A of the frame 10; and a dust cap 17B formed in the central portion of the diaphragm 17. Such a speaker device 1J is attached to an attachment base through an attachment member 20J, in a manner shown in FIG. 1.
On the other hand, various efforts have been made to improve the attachment member 20J so as to set the speaker device within a limited space in a more efficient way.
For example, a cylindrical reinforcing rib 23J is formed on the attachment member 20J to increase an attachment strength, as shown in FIG. 1. However, an internal cylindrical space defined by the inner wall 23Ja of the reinforcing rib 23J can disturb a sound characteristic of the speaker. In detail, as shown in FIG. 1, an air vibration is generated under the diaphragm 17 due to the vibration of the diaphragm 17 and such an air vibration will produce a resonance phenomena in the cylindrical space defined by the reinforcing rib 23J through an opening 10B of the frame 10. In fact, such a resonance phenomena can increase a sound pressure in one specific frequency band but can reduce a sound pressure in another frequency band, thus undesirably enlarging a difference between peak and dip in an entire frequency band. Further, as shown in FIG. 1, an air flow generated through the vibration of the diaphragm 17 will be impeded by the inner surface 23Ja of the reinforcing rib 23, undesirably restricting the movement of the diaphragm 17 and thus resulting in a low sound characteristic.
Moreover, where a loud-sound speaker is equipped with an electronic device such as a capacitor which is for use in a high pass filter in order to control a signal being supplied to the speaker, such an electronic device is directly connected by soldering to a speaker terminal section in the speaker frame, so as to ensure an appropriate installation of the electronic device within a limited space. However, it is still difficult to install a large size capacitor or a plurality of electronic devices in a limited space close to the speaker.